My last two new courses in the USA were 4.0M and $4.4M, although that has been awhile. Both on clay, some clearing, one a housing course that had a long stretch of pipe, cart paths, etc. Irrigation keeps going up, and its hard to get a system for less than $1.5M
My current and most recent total blowouts of existing courses cost $7M (w sand cap fw), $3.6M, $4.2M (with union labor and some topsoil issues, but cheaper irrigation) I have done 18 hole green and tee renos for $1.9M and $3.6M, which excluded irrigation because it was fairly new.
I build a mid level course - not cheap or skimp on the basics, but not Mercedes Benz either, in most cases. As you can tell, site and regional factors - mostly labor rates and materials like sand, gravel can vary a lot. Most prices pretty standard, except for irrigation, drain pipe, and anything hauled to the site (which is most stuff) by truck, with fuel prices soaring over the last few years.